The present invention relates to a system according to the preamble of Claim 1 as well as to a use of the system.
Magnetic couplings are used for transmitting the torque between shafts which are not in contact with one another. This means that a rotary transmission to be sealed off, as required, for example, for the drive shaft extending out of the housing in the case of a gear pump, will not be necessary in the case of a gear pump having a magnetic coupling. Pumps driven by means of magnetic couplings have only statically acting seals. They are therefore considered to be hermetically sealed and are suitable particularly for toxic pumping media or pumping media extremely harmful to the environment.
Known magnetic couplings consist of a bell-type outer rotor, the single-walled or double-walled separation pot and the inside rotor. The outer rotor is normally disposed on a motor shaft or a transmission output shaft, and the inner rotor is situated on the drive shaft of the gear pump which extends out of the pump housing. The torque transmission takes place by magnets which are situated on the interior surface of the outer rotor as well as on the exterior surface of the inner rotor. Because of the above-mentioned application advantages, magnetic couplings of this type are used increasingly and preferably also for continuously increasing powers to be transmitted.
A disadvantage of this known embodiment are the high demands made on the position of the components to be mutually connected: Thus, the drive unit as well as the gear pump have to be positioned with respect to one another in an extremely precise manner. Since gear pumps must also be connected with connection pipes for the pumping medium to be transported, further limitations or indications occur here with respect to the desired position which often do not coincide with the former. A remedy is provided here by the possibility that the drive unit can be mounted in a simple manner, which, however, is practical only in the low-power range.
In the case of high transmission powers, the mounting of the magnetic coupling is difficult because the magnets have a very strongxe2x80x94and therefore heavyxe2x80x94construction. The assembling of the components is designed such that the respective last-mounted rotor must be pushed along the separation pot. In this case, the corners of the driving magnets made of a usually brittle magnetic material splinter very easily.
It is therefore an object of the present invention to provide a system which has a magnetic coupling which does not have the above-mentioned disadvantages.
This object is achieved by the measures indicated in the characterizing part of Claim 1. Advantageous embodiments of the invention as well as a use are indicated in additional claims.
The invention has the following advantages: Because the shaft driven by the driving unit is connected in an articulated manner with the drive-side rotor and because the axis of the drive-side rotor is radially fixed by way of fixing elements which are preferably constructed as roller bearings, the axis of the driven shaft and that of the drive-side rotor do not have to coincide. On the contrary, these may have a lacking alignment without any impairment of the functioning of the overall system.
Another embodiment of the invention, in which the bearing points, that is, the roller bearings, are arranged radially with respect to the separation pot of the magnetic coupling, additionally has the advantage that, during the assembly of the magnetic coupling, its outer rotor, guided by the fixing elements, can be pushed over the separation pot without the possibility of a tilting. This embodiment of the invention also has the advantage that the outer rotor bearing is closer to the separation pot and thus to the site where a precise positioning, particularly in the radial direction, is decisive for the functioning.